A number of methods are available for the automated or semi-automated processing of photographic elements containing one or more light-sensitive silver halide emulsion layers on a support. As used herein the term "processing" is intended to include any step for handling or processing the element, whether in connection with the manufacture or development processing of the element. To simplify the terminology herein, it is assumed that the desired orientation for processing is with the support on the bottom and with the light-sensitive layer(s) on the top, and therefore reference to the top of the element means the side of the support where the sensitized layers are intended to be during processing. Of course, if the sensitized layers are intended to be other than on the top of the support during processing, top would refer to that intended side.
Automated processing in the form of so-called "minilabs" are located in supermarkets, shopping malls etc. to accomplish the automatic and accurate processing of film to provide color prints and slides. Professional offices use automated equipment to process x-rays in order to provide prompt, accurate diagnoses. In any of these systems, it is desirable to be able to automatically detect the presence of a photographic element to be processed so that the presence can be used to control a handling or processing step. For example, detecting the presence of the element in a particular location may help: determine the size of the element; detect defects in the element, perforations, etc.; count the number of elements processed; activate transport of the element to the next station for processing; turn on dryer motors to dry the element following processing; activate chemical replenishment of the processing baths; initiate splicing of the element to the preceding element for ultimate batch processing etc.
The commonly used method for detecting the presence of the photographic element is through transmissive infrared ray detection. A ray emitter is located on one side of the element and a detector on the other side. When the element is transported to a position between the emitter and detector, the ray is not transmitted because it is absorbed by the element in its path. The absorption is accomplished in part by the silver present in the element and also in part by the other film components such as absorber dyes, gel etc.
This method of detection presents problems with modern film technology. Advances in silver halide technology have resulted in the use of photographic elements which have become increasingly thinner. Moreover, the silver levels in film have been steadily reduced in order to reduce raw material costs and in order to reduce the emission of heavy metals associated with processing and disposal of silver halide materials.
As a result of modern advances, it has become a problem with certain equipment that the levels of silver and other components contained in photographic elements have been reduced to such an extent that the photographic element cannot be detected by use of the transmissive infrared detector method. Even when the element is present, it is so thin that the infrared ray is largely transmitted through the element which results in the element not being detected. While the equipment can readily handle thicker elements, it will not function properly when a thin film is processed. In some cases it may be possible to override the automatic control when a thin element is to be processed, but it is desirable to be able to rely on a completely automatic system. In other cases it may be possible to adjust the sensitivity of the infrared transmissive detector, but this may entail costly technical assistance. Further, as films become increasingly thinner, the sensitivity needed to detect the difference between the absence and presence of the element makes the system more subject to error as a result of noise or distortion.
A film splicing device available on the market uses detectors of transmitted infrared rays to ascertain the presence of film to be processed. The device also uses a single detector of reflected infrared rays located on the support or bottom side of a properly oriented photographic element to be processed as a means of determining whether the element has inadvertently been spliced with the wrong side up. This misorientation is undesirable since the rollers or other means used to transport the element should contact the support side of the element in order to avoid scratching the imaging layers during process, undesirably degrading the image. This device and method do not employ the detection of infrared rays reflected from the top or imaging layer side of the support.
It is a problem to be solved to provide a method and device for the reliable detection of both conventional and thin film during the handling and processing of a photographic element.